How is Knowledge of Qualia Possible?

03/12/13

How is Knowledge of Qualia Possible?

This post continues the series on consciousness and qualia. In an earlier post I concluded that the experience of phenomenal consciousness includes qualia, which are not reducible to anything physical/material. In my last post I gave a partial solution to one of the main aspects of the so-called “hard problem of consciousness”, which is what makes qualia possible and how this relates to the physical body, including the brain.

Both John Searle and David Chalmers are proponents of the idea of qualia. They both appear to be certain that qualia are real and that because of this zombies are a logical possibility. Both appear to be certain that they are not themselves zombies. This leads to what Chalmers calls the paradox of qualia judgment: If one is certain that they are not a zombie, and yet one’s zombie twin would in theory be physically identical to them, how then can one know about their own phenomenal consciousness while the zombie does not, since this knowledge is a physical brain state? And if one believes, for the sake of making the zombie twin completely physically identical to one’s self, that the zombie would also insist that it has phenomenal consciousness even though it does not, then how can one be epistemically justified to believe they indeed have phenomenal consciousness?

Chalmers believes that his zombie twin would also be theorizing about phenomenal consciousness just the same as himself even though it has no experience of this. He says that he is justified in concluding that he is not a zombie because he has conscious experience. “From the first-person point of view, my zombie twin and I are very different: I have experiences, and he does not. Because of this, I have evidence for my belief where he does not. Despite the fact that he says the same things I do, I know that I am not him…because of my direct first-person acquaintance with my experiences.”

The only way that Chalmers could be justified in saying this is if there were properties of phenomenal consciousness that he could discern from introspection. It seems that he could not actually be justified in his conclusion unless he were perceiving some sort of sense data that directly indicate that they have certain properties – properties that cannot be reconciled with the material substance that must also exist. This makes the zombie twin thought experiment problematic because in a situation where a zombie does not have the experience of qualia it is difficult to imagine how this zombie could also have this sense data that indicates certain nonphysical properties. The most reasonable conclusion, given the assumption that someone could be justified in saying that they experience nonphysical qualia, is that this person is making this judgment partially on the basis of unique sense data that any zombie could not have access to. Otherwise, the zombie actually would experience qualia and therefore would not be a zombie after all. So in this case a zombie twin could be similar to one's self in every way except for the sense data that causes one to be justified in their beliefs regarding the properties of qualia.

Epistemic justification is only one requirement for knowledge. Another requirement for a belief to be considered knowledge is that a belief must ultimately be caused by the thing that the belief refers to. This means that in order for one to actually have knowledge of qualia, there must be a genuine causal chain from the actual instances of qualia to the belief that one has about the qualia. This is very problematic because it has already been concluded that qualia must be nonphysical. Despite this, for one to have knowledge of them, they must have a causal effect on the physical world because one's beliefs are a part of their physical brain. Getting back to Chalmers' insistence that he has knowledge of a nonphysical aspect of his consciousness, it is clear that it is his brain that believes in this and his physical body that reports on this beliefs to others. If he does indeed have knowledge that there is more to his consciousness than that which can be reduced to the physical, then this can only be possible if his brain had another sense of some sort, distinct from the traditional five and any others that can be studied scientifically, and through which he can understand more about his experience than what is physically possible. The brain, being purely physical, does not have the ability to have a nonphysical experience, but there might be some mechanism through which it can understand the distinction between its own physical sense data and a qualitatively different nonphysical experience.

Chalmers concedes that qualia is likely an epiphenomenon, which means that it is caused by the physical world but that this causation is only one way because the physical world appears to be causally closed. But if qualia were epiphenomenal, they could not then have any causal effect on the physical world. Since an epiphenomenon can only have a one-way causal relation by definition, it is not logically possible for any instance of qualia to be an epiphenomenon and also for its existence to have any effect on the someone's brain and therefore a person could never actually have knowledge that qualia exist. Since Chalmers insists that he has knowledge of the nonphysical aspect of consciousness including many instances of qualia because of his own experiences, this means that qualia cannot merely be epiphenomenal and instead there must be some effect on the physical brain when qualia occurs.

Since it has been concluded that qualia exist as the nonphysical aspect of experience, there must be a way for the physical brain to know about their existence. The most reasonable solution to the Knowledge of Qualia Problem is as follows: 1) sense data is picked up by the bodily organs, such as the eyes and ears, and causes all of the brain events associated with perception. 2) There is then a nonphysical experience that is somehow caused by this, which are qualia. 3) The brain then uses a sense that is distinct from the traditional five senses and any other senses that can be studied scientifically to come to know certain properties of the qualia that were just experienced. 4) The brain discerns that the properties of the qualia are ontologically distinct from material substance, which it came to know about through other means. 5) With this knowledge, the brain is able to report on it. This solution to the Knowledge of Qualia Problem is called interactionism because it involves bidirectional interaction between the physical and the nonphysical.

Interactionism is not completely consistent with Chalmers’ theory because the zombie twin would not be able to report on any nonphysical experience because no such thing happens from the point of view of a zombie. Therefore, a zombie cannot be 100% physically identical to a body that has phenomenal consciousness. The two can be almost completely identical, but one will have to acknowledge that there must be a single exception in that the latter would have to have a special sense with which it gains more information about experience than what is physically possible.

Searle has a different solution to the epiphenomenon problem in which he argues that although qualia cannot be ontologically reduced to the physical body that they can be causally reduced to physical interactions. Searle argues that all of the causal relations between one's qualitative experience and the physical interactions within one's brain are the same thing and that therefore no epiphenomenon occurs. To elaborate, there are regular physical interactions going on within the brain and the qualitative experience, according to Searle, is a part of those.

Searle's answer to the Epiphenomenon Problem, however, is internally inconsistent. Searle would agree with the following points 1) Qualia are ontologically distinct from the material stuff that the brain is made of. 2) There are are a lot of physical interactions going on within the brain. 3) When these brain events occur, such as when one sees something, hears something, feels pain, etc., there are instances of qualia that are caused to exist that are not the same thing as any particle of matter that is a part of the brain nor any collection of such particles. If qualia are ontologically distinct from the physical body but are caused to exist by interactions in the physical body, then it would be inconsistent to say that the physical body is causally reduced. Also, Searle's theory of biological naturalism is not immune to the paradox of qualia judgment and thus cannot solve the Knowledge of Qualia Problem without concluding that qualia somehow have a causal effect on the brain so that one can know about their existence and argue that they are ontologically distinct, as Searle does.